Recent advancements in digital signal processing technology have been accompanied by progress in the digitization of video signals. Along with this, in addition to the analog data signals of standard television broadcasts, digital data signal broadcasts via satellites are now starting to be realized, creating a demand for media to record and reproduce these broadcast data signals.
On the other hand, home VTRs (VCRs) for recording and playing back standard analog video and audio signals are already in widespread use throughout the world, and an enormous amount of recorded material for these systems already exists in analog format. What is needed is a hybrid method and system that not only can record and play back the new digital data signals, but can also play back this enormous volume of existing recorded material. In other words, what is needed is a system that is "downward compatible" with the current analog VTRs, but is also "upward compatible."
Proposed in Japanese Laid-Open Patent Application No. H8-63875 (1996), as a VTR capable of handling both analog and digital formats, is a recording and playback system that can automatically determine the signal format of the signals being played back from a recording storage medium on which a mixture of both analog and digital signals are recorded.
Such a recording and playback system, however, is concerned only with automatically determining the signal format of signals being played back from a storage medium on which a mixture of both analog and digital signals were recorded. There is nothing in this disclosure that suggests means or a method for selectively recording analog and digital data signals.
That is, because the signal processing performed to record digital data signals differs from that performed for analog signals, it is preferred to use different recording media when recording digital and analog signals. Nothing is included in the above-noted application, however, that suggests a way to select the digital/analog data signal processing to be performed during recording, based on the performance specifications of the recording medium.
Therefore, there is a need to propose a data signal recording and playback method and system wherein, with recording media for recording analog data signals classified as "standard performance" media, and recording media for recording digital data signals classified as "high-performance" media, the system would be capable of sensing the performance level specification of the medium and performing the best signal processing for that medium for the type of signal being recorded.
Also, while it is, of course, better to use a digital recording technique to record digital data signals, there is also a need for a system that, in addition to identifying the recording medium, as discussed above, also provides the capability to use an analog recording technique to record digital data signals, in order to maintain compatibility with existing analog VTRs that, as previously mentioned, are in such widespread use throughout the world.
Such analog and digital VTRs must be designed with an emphasis on how the consumer will be using the systems. For example, the systems will have to provide the capability to receive digital and analog broadcasts and either view them on an external display device such as a video monitor, or send them to external recording and playback equipment. Also, in addition to switching the individual analog and video signal outputs to their respective connectors, users will also want the capability to convert digital signals to analog signals for output. In short, these new video digital/analog hybrid systems will require a variety of output switching functions.
So far, no technology has been disclosed for the above recording and playback systems for automatically recognizing the recording storage media formats for recordings having a mixture of digital and analog signals in addition to performing the above output switching functions.
Accordingly, the method and apparatus incorporating the principles of the present invention provides, for VTRs that accommodate signals in both analog and digital format, a data signal recording and playback system that is capable of performing a variety of output switching functions, including the conversion of digital signals to analog signals prior to output. More specifically, the embodiments of the present invention provides a data signal recording and playback system wherein all required output switching is performed within the recording and playback system itself, so that display switching, etc., need not be performed in external display devices such as video monitors.